android 自定义的小工具类（1）获取图片和视频的缩微图

public Bitmap getImageThumbnail(String uri, int width, int height){
        Bitmap bm = null;
        //缩略图
        BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;//设置为true, 不会返回位图， 但仍会设置字段， 允许查找位图而不分配内存
        //获取原图，将uri路径的文件解析成bitmap ,
        bm = BitmapFactory.decodeFile(uri, options);
        //设置缩略图之后，将inJustdecodeBounds设置为false, 再获取位图，就是获取一个缩略之后的位图
        options.inJustDecodeBounds = false;
        int beWidth = options.outWidth/width;
        int beHeight = options.outHeight/height;
        int be = 1;
        if(beWidth < beHeight){
            be = beWidth;
        }else {
            be = beHeight;
        }
        if(be <= 1){
            be = 1;
        }
        /**
         * If set to a value > 1, 
         * requests the decoder to subsample the original image, 
         * returning a smaller image to save memory. 
         */
        options.inSampleSize = be;
        //重新获取bitmap， 这个时候获取的就是缩略图
        bm = BitmapFactory.decodeFile(uri, options);
        //创建一个指定width,height的位图
        bm = ThumbnailUtils.extractThumbnail(bm, width, height, 
                ThumbnailUtils.OPTIONS_RECYCLE_INPUT);
        return bm;
        
    }
    

　//kind MediaStore.Images.Thumbnails.MICRO_KIND   
 public Bitmap getVideoumbnail(String uri, int width, int height, int kind){
        Bitmap bm = null;
        bm = ThumbnailUtils.createVideoThumbnail(uri, kind);
        bm = ThumbnailUtils.extractThumbnail(bm, width, height, ThumbnailUtils.OPTIONS_RECYCLE_INPUT);
        return bm;
    }